Hi Gloria,
Please see below resolution:
This issue is not critical and only is needed when using HTTPS access.
Link below for creating self-signed certificates:
http://www.cisco.com/c/en/us/td/docs/ios/12_2sr/12_2sra/feature/guide/srpkissc.html
If there is no need for you to use it, please type the following command: no ip http secure-server
Hope it helps.
Please rate it if this info is useful to you.
regards,
Ben